1. Technical Field
The present invention relates to a liquid ejecting apparatus that forms an image on a recording medium by ejecting liquid.
2. Related Art
An ink jet type printer (hereinafter, it is referred to as an ink jet printer) has been used as an example of liquid ejecting apparatuses, which forms an image by scanning a printing head having a plurality of nozzles for forming dots in a main scanning direction, ejecting liquid, and transporting a recording medium in a sub-scanning direction intersecting the main scanning direction. Such an inkjet printer, for example, repeatedly forms an area (hereinafter, it is referred to as a band) having a width depending on a length of arrangement of the plurality of nozzles of the printing head, repeatedly transports the recording medium in the sub-scanning direction in accordance with the band width during a single scanning of the printing head, and arranges bands in the sub-scanning direction so as to bring an end portion of one band into contact with an end portion of the other band formed by the next scanning, thereby forming an image. Such a printing method is called “band printing method”.
However, in the band printing method, sometimes stripes appear at the boundaries between the bands. The stripes cause deterioration in image quality of the image formed on the recording medium. To suppress the deterioration in image quality caused by the stripes appearing at the boundaries between the bands, for example, a process as described in JP-A-H06-47925 has been performed. In the process, the lower end portion of a previous band formed by a first scanning of the printing head is overlapped with the upper end portion of a next band formed by the next scanning of the printing head, and thereby some dots of the lower end portion of the previous band firstly formed are formed during the scanning operation for forming the next band, and some dots of the upper end portion of the next band secondly formed are formed during the scanning operation for forming the previous band. Hereinafter, the process is referred to as a partial overlap (POL) control.
However, sometimes a blank area, in which any dot is not formed in the whole range of a plurality of successive main scanning lines, exists in an image to be formed on a recording medium. In this case, there has been known a technique for shortening printing time by performing a blank skip process which transports the recording medium by a large feed amount depending on a width of the blank area so as to skip the blank area in scanning. However, there is a problem in that image quality of a printed image is deteriorated when the blank skip process is applied during a printing process in which the POL control is being performed. The reason why image quality is deteriorated is that, for example, some dots of the lower portion are not formed and one band formation is terminated when the blank skip process is applied in the case where a nozzle for forming intermittent dots on the lower end portion of a band, and pixels in the boundary portion between the blank area and the image forming area are not printed.